DAVOS, Switzerland, Jan 25 (Reuters) - The U.S.-led invasion of Iraq in 2003 was an "idiot decision" and Iraqi troops now need to secure Baghdad to ensure the country's future, Vice-President Adel Abdul Mahdi said on Thursday.

"Iraq was put under occupation, which was an idiot decision," Mahdi said at the World Economic Forum in Davos.

Mahdi said the Iraqi government planned to bring troops in to Baghdad from surrounding areas and said it was "a technical question" for the United States to decide whether to deploy more soldiers.

President George W. Bush plans to send another 21,500 troops to Iraq, a move widely criticised in the United States. On Wednesday, the Senate Foreign Relations Committee voted against the decision, which is due to go before the Senate next week.

"If we can win this war in Baghdad then I think we can change the course of events," Mahdi told a panel on the state of affairs in Iraq.

"As Iraqis, we think we need more (Iraqi) troops in Baghdad, and we are calling for some regiments to come from other parts of the country," he said.

Mahdi's party, the powerful Shi'ite Supreme Council for Islamic Revolution in Iraq, was one of the exiled opposition parties consulted by Washington as it planned the invasion.

Its leader Abdul Aziz al-Hakim is a key figure behind the U.S.-backed national unity government.

MORE CHAOS?

Some commentators are concerned that without the support of U.S. troops in Iraq, the already boiling sectarian violence between Sunnis and Shi'ites could break out into ever greater killing sprees.

Adnan Pachachi, a member of Iraq's parliament and a former acting speaker, said that if the United States could not stay in Iraq, other troops should be drafted in. "If because of domestic pressure in the United States, the U.S. feels it is not possible to continue undertaking this burden, then I think we should consider going to the United Nations and having an international force," said Pachachi.

"This is a last resort really, otherwise there would be total chaos in the country."

Bush, who this week pleaded for the United States to give his new Iraq plan a chance, does not have to abide by a Senate resolution if legislators vote against sending more troops.

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